I hope I don't hate the IRF's
You won't hate them. Just a slightly different flavor.
IRFs are more critical or sharper.
I thought the Fairchilds were suppose to be sharper and brighter w/less 2nd harmonic distortion in the midband. I've heard the IRF's are darker and more "tubey".
Regardless, I hope I like them. But I have a feeling Toshibas will be going in someday. I just can't seem to leave this amp alone.
Regardless, I hope I like them. But I have a feeling Toshibas will be going in someday. I just can't seem to leave this amp alone.
Got everything put back together. New thermistors, New IRF mosfets, new Jfets, new ztx 450/550.
Damn thing won't bias.
P2 does nothing. I can get the bias up to .5V w/P1 but the offset remains around 700mv. And P2 wont bring down the offset and has now effect on bias.
Nothing smoked or hot. PS is spot on 24V.
What now? No resistors are open. Both channels exhibit this behavior.
Fried P2 pots? is thing is driving me crazy...
Damn thing won't bias.
P2 does nothing. I can get the bias up to .5V w/P1 but the offset remains around 700mv. And P2 wont bring down the offset and has now effect on bias.
Nothing smoked or hot. PS is spot on 24V.
What now? No resistors are open. Both channels exhibit this behavior.
Fried P2 pots? is thing is driving me crazy...
All fixed. The P2 trimpots were fried (thanks Audiosan)
Lessons learned:
Make sure the tips (sensor) of your thermistors are not conductive. And if they are, make sure they contact the plastic body of the mosfet only. Don't let them touch the bolt/washer.
Since it took me a month to fix the amp my memory is not so good but the change from Fairchild to IRF mosfets doesn't seem to be that big of deal. I could be imagining things but the Fairchilds seem more detailed and extended and the IRF's seem to have more midrange body. Not a back-to-back test though, there was a month between listening to them.
Lessons learned:
Make sure the tips (sensor) of your thermistors are not conductive. And if they are, make sure they contact the plastic body of the mosfet only. Don't let them touch the bolt/washer.
Since it took me a month to fix the amp my memory is not so good but the change from Fairchild to IRF mosfets doesn't seem to be that big of deal. I could be imagining things but the Fairchilds seem more detailed and extended and the IRF's seem to have more midrange body. Not a back-to-back test though, there was a month between listening to them.
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